This study is a single-center, parallel-group, randomized controlled trial with the following objectives: to compare the incidence of post-operative descemet membrane detachment (DMD) in phacoemulsification surgery between modified and conventional 2.2mm microincision.

2.2mm incision is considered an ideal incision size in phacoemulsification. However, DMD is a common and serious complication in 2.2mm microincision phacoemulsification for hard nucleus age-related cataract. DMD is originated from the incision in the operation. How to construct the appropriate incision shape and size for reducing the occurrence of DMD is an important problem to be solved urgently in phacoemulsification surgery.

The investigators found that enlarging the internal incision could increase the range of motion of surgical instruments and reduce the friction of instruments to incision. Therefore，the incidence of DMD would be reduced. The investigators developed this technique, modified 2.2mm incision, to reduce the incidence of incision-site DMD and not to increase other incision related complications.

In this trial, the investigators aim to compare modified and conventional 2.2mm incision with regard to safety and efficacy in reducing the incidence of DMD.

Inclusion Criteria:

• Aged-related cataract patients between 65 and 90 years ;
• Lens nuclear opalescence grade ≥4.0 on the Lens Opacities Classification System III (LOCS III);
• Scheduled for phacoemulsification combined with intraocular lens implantation.
• The number of corneal endothelial cells > 1500cells/mm2.
• Dilated pupil diameter ≥6mm

Exclusion Criteria:

• A history of ophthalmic trauma or surgery;
• Other ophthalmic diseases such as glaucoma, uveitis, high myopia;
• Ocular factors that would make surgery challenging or dangerous, including but not limited to small pupil, shallow anterior chamber, etc.